Data transmission device, data transmission method, game device, and game system

ABSTRACT

A game device ( 10 ) can transmit AV data of a game to a receiving terminal ( 20 ) by adaptively setting the communication protocol. The protocol setting is performed according to the scene state in the AV data and the propagation environment such as the transmission error rate. For example, by using UDP for a high real-time game scene and TCP for a low real-time game scene, it is possible to effectively transfer the AV data to the receiving terminal(20) without impairing the continuity of the game.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of International application PCT/JP04/005368 filed on Apr. 15, 2004, pending at the time of filing of this continuation application and claims priority from Japanese Patent Applications 2003-112218 filed on Apr. 16, 2003, the contents of which are herein wholly incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to communications technologies, and more particularly to a technology for implementing communications between a plurality of terminals over a network.

2. Description of the Related Art

In performing communications between terminals over a network, it is necessary to define a protocol which specifies rules for the communications. The protocol for establishing network connections include a connectionless protocol such as UDP (User Datagram Protocol) which requires neither establishment nor release of a transmission path before and after transmission and a connection oriented protocol such as TCP (Transmission Control Protocol) which requires establishment and release of a transmission path before and after transmission.

In the Internet, UDP and TCP are set as the protocols of the fourth layer (transport layer) In performing communications over the Internet, either the UDP or TCP protocol, which is preset as the communication protocol in the transport layer, is followed for data transmission. Once set, the protocol is intended not to be changed but to accommodate variations in the propagation environment, if any, by reducing the transmission rate.

The aforementioned communication protocols are concerned with the Internet representative of WAN (Wide Area Network). Likewise, for LAN (Local Area Network), one communication protocol is preset, which is followed for data transmission.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a communications technology which employs an inventive method of setting a communication protocol. To this end, the communications technology according to the present invention enables setting of a protocol to be used as circumstances demand.

One aspect of the present invention relates to a data transmission device for transmitting data to a receiving terminal over a network. This data transmission device enables setting of a protocol to be used from among a plurality of data transmission protocols. The data transmission device may set a protocol based on preset instruction information associated with the data to be transmitted. When the data is image data, the instruction information may be protocol setting information preset for the image data or protocol setting in formation preset for a scene made up of the image data. The protocol setting information may take the form of a flag designating a protocol or information for identifying the title or genre of the image data. The protocol may also be act based on an instruction from the user.

Alternatively, the protocol may also be set based on the transmission error rate of the data received by the receiving terminal.

Another aspect of the present invention relates to a data transmission method for transmitting data to a receiving terminal over a network. This data transmission method enables setting of a protocol to be used from among a plurality of data transmission protocols.

Still another aspect of the present invention relates to a game device for transmitting AV data of a game over a network to a receiving terminal having a display and a speaker. The game device enables setting of a protocol to be used from among a plurality of data transmission protocols. The game device may employ UDP for transmitting AV data of a game or AV data of a scene of a game requiring a low delay, whereas employing TCF for transmitting AV data of a game or AV data of a scene of a game not requiring a low delay.

Still another aspect of the present invention relates to a game system which includes a receiving terminal having a display and a speaker, a game device for transmitting AV data of a game to the receiving terminal over a network, and a game device controller controlled by a user. In this game system, the game device enables setting of a protocol for transmitting the AV data to the receiving terminal based on preset protocol setting information associated with the AV data or a transmission error rate. The game device may also enable changing of the protocol according to an entry on the controller.

Still another aspect of the present invention provides a program which allows a computer to execute a function for enabling setting of a protocol for data transmission over a network from among a plurality of protocols.

Still another aspect of the present invention provides a computer readable recording medium on which stored is a program that allows a computer to execute a function for enabling setting of a protocol for data transmission over a network from among a plurality of protocols.

Incidentally, any combinations of the foregoing components, and any conversions of expressions of the present invention from/into methods, apparatuses, systems, recording media, computer programs, and the like are also intended to constitute applicable aspects of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing an overall configuration of a game system according to an embodiment of the present invention;

FIG. 2 is a view showing a TCP header format;

FIG. 3 is a view showing a TCP/IP communications model;

FIG. 4 is a view showing a UDP header format;

FIG. 5 is a view showing the configuration of a game device;

FIG. 6 is a view showing an example of a DMA mode register;

FIG. 7 is a view showing an example of a DMA control register;

FIG. 8 is a view showing the system configuration of a receiving terminal;

FIG. 9 is a view showing a typical functional configuration of a game device according to the embodiment;

FIG. 10 is a table showing the relation between a game genre and the presence or absence of a low delay requirement:

FIG. 11 is a table showing the relation between a game title and the presence or absence of a low delay requirement;

FIG. 12 is a view showing an RTP header format; and

FIG. 13 is a view showing an example of a PROTOCOL designating bit in the DMA control register.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows the overall configuration of a game system 1 according to an embodiment of the present invention. In the game system 1 according to this embodiment, a game device 10 serves as a data transmission device for transmitting data to a receiving terminal 20 over a network 40. The game device 10 and the receiving terminal 20 may be connected to each other wirelessly or by cables For example, the network 40 may take the form of a home network made up of network (LAN) cables or a wireless LAN.

In the game system 1, the AV (Audio visual) data of a game transmitted by the game device 10 is received at a transceiver 22 of the receiving terminal 20, allowing the game video image to be displayed on a display 30 and the sound to be delivered from a speaker 32. The transceiver 22 may be integrated with an output device such as the display 30 and the speaker 32. The game device 10 and the receiving terminal 20 connected wirelessly to each other could be laid out relatively freely, when compared with those wired such as by cables, thereby allowing the user to enjoy games without being limited to a particular location. Additionally, a wireless controller employed as an input interface for controlling a game could allow the user to enjoy the game at a user's favorite place. At this time, the game device 10 processes a control signal from the wireless controller to produce the AV data of a game for transmission to the receiving terminal 20. Alternatively, the transceiver 22 may have a function of receiving the control signal for transfer to the game device 10. In particular, the transceiver 22 may preferably have this functionality when a weak control signal is only available from the wireless controller. The controller may also be wired to the game device 10 or the receiving terminal 20.

In this embodiment, the game device 10 enables setting of a protocol to be used from among a plurality of data transmission protocols. In the following descriptions, it is to be understood that the game device 10 sets the transport layer protocol of the OSI (Open Systems Interconnection) model as the transmission protocol. The transport layer specifies a set of rules for ensuring the reliability of data transfer, and includes TCP and UDP.

FIG. 2 shows a TCP header format. TCP first confirms a partner to be connected and then transmits or receives packets across the connection, thereby realizing highly reliable communications TCP/IP utilized as a standard Internet protocol and made up of two protocols, i.e., TCP and IP (Internet Protocol), executes the following communications procedures:

(1) A transmitting terminal makes a connect request, and a receiving terminal receives the request and then initiates the connection.

(2) The transmitting terminal adds additional control information called a “header” to data in each layer of the OSI model to create a packet for transmission.

(3) when the data passes through each layer in the receiving terminal, the corresponding header is confirmed and then removed, and the resulting data is finally passed to the application layer. In this process, the receiving terminal refers to the TCP header to confirm whether the packet has been successfully received. If the packet has been received unsuccessfully or found to include an error, the receiving terminal issues no acknowledgement. In this case, the transmitting terminal retransmits the packet. After all pieces of data have been completely transmitted from the transmitting terminal, the connection is released.

The sequential number of the TCP header refers to the orderly position of the pieces of data transmitted and is incremented by the octet number of the transmitted data each time the data is transmitted. The acknowledgement number refers to the sequential number of data to be received next. Accordingly, in any TCP-based communications, it can be confirmed that the transmission is successfully performed, when the sequential number to be sent next agrees with the returned acknowledgement number.

FIG. 3 shows a TCP/IP communications model. This communications model is intended to be applicable to communications over Ethernet (registered trademark). The transmitting terminal allows the application layer to generate data, the transport layer to add a TCP header to the data, the internet layer to add an additional IP header to the data, and the network layer to add an additional Ethernet header to the data. The resulting data is finally transmitted to the receiving terminal over the network 40. The receiving terminal allows the network layer to remove the Ethernet header, the internet layer to remove the IP header, and the transport layer to remove the TCP header. Then, the resulting data is passed to the application layer. The aforementioned communications procedure allows data to be transmitted from the transmitting terminal to the receiving terminal. In this embodiment, the game device 10 corresponds to the transmitting terminal and the receiving terminal 20 corresponds to the receiving terminal.

FIG. 4 shows a UDP header format. The UDP/IP, utilized for the Internet and made up of two protocols, i.e., UDP and IP, does not include the TCP's functions such as confirming of the establishment of a connection and retransmitting of data. When compared with the TCP header shown in FIG. 2 where the TCP header is made up of 24 bytes, the UDP header is made up of 8 bytes. The receiving terminal analyzes the header to process the packet. Since the UDP header is shorter than the TCP header, the former can be processed in a shorter time by that amount.

Now, consideration will be given to the properties of TCP and UDP in a path in which packet errors are likely to occur frequently during data transmission. If a packet transmitted from the transmitting terminal is lost, TCP will follow the aforementioned procedure to retransmit the packet. The retransmission means that the real-timeliness of processing the data is significantly degraded at that point in time. Accordingly, when TCP is used to transmit AV data of a game, symptoms such as a freeze-up may appear in the video images displayed on the display 30.

When a bit error occurs in the payload or the data portion of a packet, both TCP and UDP can detect the error using the checksum. When an error is detected, the packet will be discarded. According to the current standards, UDP can turn off the checksum whereas TCP cannot turn it off. That is, even when a mere one bit error occurs in the data payload, TCP discards the entire packet and retransmits the packet, whereas UDP turns off the checksum thereby allowing the data including one bit error to be processed as it is and then passed to the upper layer. From this, UDP is found to be more favorable than TCP in terms of real-timeliness. From a different point of view, it can also be seen that TCP performs retransmission and is thus more favorable than UDP when a high level of real-timeliness is not required.

In this embodiment, in transmitting the AV data of a game to the receiving terminal 20, the game device 10 adaptively sets a data transmission protocol. More specifically, based on the data to be transmitted or the instruction provided by the user, the game device 10 adaptively selects either TCP or UDP as the protocol of the transport layer. This makes it possible to change the protocol depending on the type of transmission data or the like, thereby realizing communications as the circumstances demand.

FIG. 5 shows the configuration of the game device 10. The game device 10 includes a media drive 100, a CPU 102, a graphics engine 104, an input interface 106, a network controller 108, a wired communication interface 110, a wireless communication interface 112, and a storage unit 114. These components are connected to each other via a bus 120. Both the wired communication interface 110 and the wireless communication interface 112 include a media access control unit (MAC) and a processing block in the physical layer (PHY). The media access control unit may be integrated with the network controller 108. For example, the wired interface includes Ethernet (IEEE802.3), while the wireless interface includes IEEE802.11b, 11g, and 11a. The CPU 102 controls the entire system.

As described above, the input interface 106 may be a game 10 controller, and is directly connected to the game device 10 by way of example. In the case of a wireless controller, a control signal from the user is received via the wireless communication interface 112. In the case of the wireless controller, a wireless block may also be added to the input is interface 106 to receive the control signal from the user via the input interface 106.

Referring to the communications model shown in FIG. 3, the application layer in the communications model corresponds to the graphics engine 104, the transport layer and the internet layer correspond to the network controller 108, and the network layer corresponds to the communication interfaces 110 and 112.

The media drive 100 drives a medium for storing game data. For example, the medium includes a CD-ROM or DVD, which stores the AV data of game scenes and game programs. The game programs may be stored in the medium in such a form that can be executed directly by the CPU 102 or executed by the CPU 102 after having been decoded. The game data stored in the medium is read from the media drive 100 into the storage unit 114 and then executed by the CPU 102.

The graphics engine 104 creates AV game data based on the game data processed by the CPU 102. This AV data is created in digital form.

The network controller 108 performs protocol stacking. This function may be realized by dedicated hardware or by software processing performed by the CPU 102. Upon reception of digital AV data from the graphics engine 104, the network controller 108 performs protocol processing on the AV data, or more specifically, adds a header corresponding to the protocol to be used to the AV data. The resulting AV data is then delivered to the network 40 via the wired communication interface 110 for wired communications or the wireless communication interface 112 for wireless communications. The protocol to be used is determined by the CPU 102.

In the game device 10, DMA (Direct Memory Access) Is employed to transmit data on the bus 120. A DMA engine is provided in the network controller 10B, and the CPU 102 sets a register for controlling the DMA engine.

FIG. 6 shows an example of a DMA mode register. Here, DEVSEL specifies a DMA target device, DMA TYP specifies the type of DMA, DMA WIDTH specifies the bit width of DMA transfer data, and DIRECTION specifies the direction of DMA. The CPU 102 sets this DMA mode.

FIG. 7 shows an example of a DMA control register. Here, STOP is a DMA stop request, START is a DMA start request, and PROTOCOL specifies a communications protocol. After having set the DMA mode as shown in FIG. 6, the CPU 102 sets the protocol for processing by the network controller 108 at a DMA control register and then sets the DMA start bit. This causes the DMA engine to be activated, allowing data to be transmitted to the network controller 108 The transmitted data is processed based on the protocol specified. As will be discussed later, this embodiment enables specifying of a protocol for a collection of data. For example, the CPU 102 can change protocols for each scene of one game.

FIG. 8 shows the system configuration of the receiving terminal 20. The receiving terminal 20 includes a CPU 200, an AV codec 202, a video DA converter 204, an audio DA converter 206, a network controller 208, a wired communication interface 210, a wireless communication interface 212, and a storage unit 214. The output from the video DA converter 204 is supplied to the display 30, while the output from the audio DA converter 206 is supplied to the speaker 32. These components are connected to each other via a bus 220. Both the wired communication interface 210 and the wireless communication interface 212 include a media access control unit (MAC) and a processing block in the physical layer (PRY). The media access control unit may be integrated with the network controller 208. The CPU 200 controls the entire system.

Referring to the communications model shown in FIG. 3, the application layer in the communications model corresponds to the AV codec 202, the transport layer and the internet layer correspond to the network controller 208, and the network layer corresponds to the communication interfaces 210 and 212.

The AV data transmitted from the game device 10 passes through the wired communication interface 210 or the wireless communication interface 212 to be subjected to protocol processing at the network controller 208. More specifically, the network controller 208 successively confirms the contents of the headers added to the AV data and then removes the headers. The resulting data is stored in the storage unit 214, and then the AV codec 202 decode: the stored AV data to convert the resulting data into AV digital data with the audio synchronized with the video. The video data is supplied to the video DA converter 204 to be converted into an analog signal and then displayed as video images on the display 30. The audio data is supplied to the audio DA converter 206 to be converted into an analog signal, which is in turn delivered as sound through the speaker 32.

FIG. 9 shows a typical functional configuration of the game device 10 according this embodiment. The functional blocks shown in FIG. 9 are implemented with each component shown in FIG. 5 or a combination of each component.

The game device 10 includes the media drive 100, a readout unit 130, an instruction information analysis unit 132, a protocol setting unit 134, a processing unit 140, the input interface 106, the graphics engine 104, the storage unit 114, and a communications unit 136. The game device 10 is implemented with a CPU, a memory, a program loaded in the memory and the like. Here, shown are the functional blocks that are implemented with these components working together. The program may be implemented in the game device 10 or stored on a recording medium and supplied externally. Accordingly, it will be understood by those skilled in the art that these functional blocks can be realized in a variety of forms, i.e. only in hardware, only in software, or in a combination thereof.

First, a medium 60 having game data stored is inserted into the media drive 100. The readout unit 130 reads the game data on the medium 50 and then stores the data in the storage unit 114. The processing unit 140 allows the game to progress based on the game data read into the storage unit 114 and the game control instruction entered by the user on the input interface 106, while the graphics engine 104 creates the AV data of the game based on the game data processed by the processing unit 140.

In this embodiment, instruction information for defining the protocol to be used is preset, associated with the AV data, in the game data stored on the medium 50. For example, the instruction information may be information on the title or the genre of the game or information for identifying a scene of the game. Furthermore, the instruction information may be a direct representation of the feature of the AV data itself or protocol setting information derived from the feature of the AV data. The protocol setting information may be a representation of the protocol to be used, e.g., a bit or flag representation of the type of the protocol. The processing unit 140 extracts the instruction information preset associated with the AV data and then sends it to the instruction information analysis unit 132. The instruction information analysis unit 132 analyzes the instruction information to determine the protocol to be used. The result of the analysis is passed to the protocol setting unit 134, which in turn sets the communication protocol.

From the viewpoint of the real-timeliness, games can be largely divided into two groups: high real-time games and low real-time games. For example, the high real-time game includes a battle game or a racing simulation game which progresses so rapidly that a control entry by the user need to be instantaneously reflected on an output such as the display 30. The low real-time game includes a match game such as Shougi (Japanese chess) or Mahjongg or a RPG (Role-Playing Game) which progresses comparatively slowly.

In transmitting AV game data over the network 40 to a high real-time game, using TCP as the communication protocol would make it difficult to realize a high real-time processing due to a delay caused by the processing itself or retransmission. Accordingly, in transmitting the AV data of such a game, the UDP protocol that does not impose heavy load on the processing may be preferably employed as the communication protocol because it is important to keep the game continuously in progress without losing its continuity even when a few bits of the image are lacked.

On the other hand, when a bit is dropped in transmitting AV data of a low real-time game, it is preferable to ensure the transmission of the packet through retransmission. Accordingly, the TCP protocol that guarantees the transmission of a packet is preferably employed as the communication protocol.

Based on the premise of the aforementioned evaluation criteria, the instruction information analysis unit 132 analyzes the instruction information sent from the processing unit 140, i.e., the instruction information preset in the game data associated with the AV data generated by the graphics engine 104. Game manufacturers create game data which incorporates the instruction information in advance corresponding to the AV data to be generated by the graphics engine 104.

To utilize the title or genre of a game as the instruction information, the instruction information analysis unit 132 analyzer, based on titles or genres sent from the processing unit 140, whether the AV data to be transmitted requires a high level of real-timeliness, i.e., a low delay.

FIG. 10 is a table showing the relation between a game genre and the presence or absence of a low delay requirement. When the instruction information sent from the processing unit 140 is related to a game genre, the instruction information analysis unit 132 refers to the table shown In FIG. 10 to determine the presence or absence of the low delay requirement for the corresponding AV data.

FIG. 11 is a table showing the relation between a game title and the presence or absence of a low delay requirement. When the instruction information sent from the processing unit 140 is related to a game title, the instruction information analysis unit 132 refers to the table shown in FIG. 11 to determine the presence or absence of the low delay requirement for the corresponding AV data. Alternatively, it is also acceptable to utilize a table that relates the title to the genre, in the case of which the instruction information analysis unit 132 may classify the genre from the title, and then based on the genre, determine the presence or absence of the low delay requirement with reference to the table shown in FIG. 10. The result of analysis provided by the instruction information analysis unit 132 is supplied to the protocol setting unit 134.

Upon reception of the analysis result, the protocol setting unit 134 sets the communication protocol. More specifically, the protocol setting unit 134 sets UDP as the communication protocol when a low delay is required or TCP when a low delay is not required. As described above, UDP is good in real-timeliness while TCP is good in ensuring transmission of data. Thus, the game device 10 according to this embodiment makes it possible to adaptively select and act the protocol that is suitable for the title or genre of a game.

In the aforementioned example, the communication protocol is set for the AV data of an entire game; however, the communication protocol may also be set according to a scene of the game. During the play of a game, some scenes may require and the other may not require a high level of real-timeliness. In a battle game, a high level of real-timeliness is required in a battle scene using characters, whereas not being required in setting the characters before the battle or in a scene after the battle has ended. It is thus possible to pre-store in the game data the instruction information indicative of the presence or absence of the low delay requirement according to these scenes. This enables the instruction information analysis unit 132 to determine, based on the instruction information preset for each scene, whether the scene requires a low delay. Even during the play of a game, the communication protocol can be adaptively changed, thereby implementing the data transmission that flexibly meets the requirement for the scene. Particularly, on the path of a wireless network on which packet errors may frequently occur, it is possible to employ UDP for those scenes requiring a low delay and TCP for the other scones, thereby implementing effective data transmission without impairing the continuity of the game.

In the foregoing, such an example was described in which the communication protocol is set based on the instruction information preset in the game data. However, this embodiment also makes it possible to change between communication protocols according to communication circumstances. Now, described below is an example in which the communication protocol is changed depending on a transmission error rate. The setting of the communication protocol according to communications circumstances can be carried out in combination with or separately from the aforementioned protocol setting based on the instruction information.

Referring back to FIG. 8, in the receiving terminal 20, the CPU 200 receives the result of the protocol processing by the network controller 208 and then measures the transmission error rate of a packet transmitted from the game device 10. The CPU 200 transmits the measured transmission error rate to the game device 10 over the network 40.

Referring back to FIG. 9, in the game device 10, the protocol setting unit 134 receives the transmission error rate from the communications unit 136. If the transmission error rate is favorable, the protocol setting unit 134 needs not to change the communication protocol. On the other hand, if the transmission error rate has been degraded, the protocol setting unit 134 determines whether or not the protocol is to be changed, based on the current protocol and the scene of the game image to be played back on the receiving terminal 20, i.e., the game image scene being transmitted. The determination of whether or not the transmission error rate is favorable can be made based on a determination of whether the transmission error rate is greater than or equal to or below a predetermined threshold level.

For example, for a still image scene or a moving image scene with fewer actions under UDP employed as the current communication protocol, the protocol setting unit 134 may determine to change the communication protocol to TCP. In this case, importance is to be placed on ensuring transmission of data thereby implementing stable data transmission. On the other hand, for a moving image scene with many actions under TCP employed as the current communication protocol, the protocol setting unit 134 may determine to change the communication protocol to UDP. This corresponds to a case where the scene requires a high level of real-timeliness but a bad propagation environment causes the TCP protocol to repeat retransmission resulting in a frozen video image. Accordingly, in this case, importance is placed not on ensuring data transmission but on real-timeliness. In particular, when a scene includes many actions but does not require a low delay, i.e., when even TCP could sufficiently cope with the scene in a good propagation environment, TCP may have been presumably set as the communication protocol to ensure data transmission. However, if the propagation environment is degraded, the protocol can be changed to UDP, thereby implementing efficient communications without impairing the continuity of the game.

Even when UDP is employed, RTP (Real-time Transport Protocol) can be used in the upper layer of the UDP, thereby providing improved communication reliability.

FIG. 12 shows an RTP header format. The RTP header includes a sequential number. Accordingly, the RTP header would enable detecting of loss or arrival turn error of packets using the sequential number, thereby providing improved communication reliability.

FIG. 13 shows an example of PROTOCOL designating bits In the DMA control register shown in FIG. 7. Two bits used to represent PROTOCOL are assigned in consideration of a case where RTP may also be used in the upper layer of UDP. The determination of whether or not RTP is added may be determined based on the transmission error rate.

In the foregoing, the present invention has been described in accordance with the embodiment. However, it should be understood by those skilled in the art that this embodiment is shown only by way of example, and a variety of modifications may be made to the combination of each component and processing steps without departing from the scope of the present invention.

In the aforementioned embodiment, by way of example, the communication protocol is set based on the instruction information preset in the game data or the transmission error rate. Alternatively, it is also possible to allow the user to set the communication protocol on the input interface 106. This allows the user to select an appropriate protocol based on the output on the display 30 or through the speaker 32.

In the aforementioned embodiment, by way of example, AV data is transmitted between the game device 10 and the receiving terminal 20; however, the present invention is not limited thereto but can also be applied to data transmission between a plurality of communication terminals. 

1. A game device which transmits AV data of a game to a receiving terminal over a network, the game device comprising: a processing unit which extracts instruction information preset in game data; an analysis unit which determines a protocol to be used based on the extracted instruction information; and a protocol setting unit which receives a result of the determination provided by the analysis unit to set a communication protocol for the AV data.
 2. A game device which transmits AV data of a game to a receiving terminal over a network, the game device comprising: a processing unit which extracts instruction information preset in game data; an analysis unit which determines the presence or absence of a low delay requirement for the AV data based on the extracted instruction information; and a protocol setting unit which receives a result of the determination provided by the analysis unit to set a communication protocol for the AV data.
 3. The game device according to claim 2, wherein the processing unit extracts a game title or a game genre set in the game data as instruction information; and with reference to a table relating a game title to the presence or absence of a low delay requirement or a table relating a game genre to the presence or absence of a low delay requirement, the analysis unit determines the presence or absence of a low delay requirement for the AV data based on the game title or the game genre extracted by the processing unit.
 4. The game device according to claim 2, wherein the processing unit extracts, from the game data, instruction information indicative of the presence or absence of a low delay requirement stored according to a game scene; the analysis unit determines whether a scene requires a low delay based on the instruction information preset for each scene; and the protocol setting unit receives a result of the determination provided by the analysis unit to set a communication protocol for each scene of the AV data.
 5. A game system comprising a receiving terminal, a game device which transmits AV data of a game to the receiving terminal over a network, and a game device controller controlled by a user, wherein the game device comprises: a processing unit which extracts instruction information preset in game data; an analysis unit which determines the presence or absence of a low delay requirement for the AV data based on the extracted instruction information; and a protocol setting unit which receives a result of the determination provided by the analysis unit to set a communication protocol for the AV data.
 6. The game system according to claim 5, wherein the communication protocol can be changed in response to an input from the controller.
 7. The game system according to claim 5, wherein the processing unit extracts, as instruction information, a game title or a game genre preset in the game data; and with reference to a table relating a game title to the presence or absence of a low delay requirement or a table relating a game genre to the presence or absence of a low delay requirement, the analysis unit determines the presence or absence of a low delay requirement for the AV data based on the game title or the game genre extracted by the processing unit.
 8. The game system according to claim 6, wherein the processing unit extracts, as instruction information, a game title or a game genre preset in the game data; and with reference to a table relating a game title to the presence or absence of a low delay requirement or a table relating a game genre to the presence or absence of a low delay requirement, the analysis unit determines the presence or absence of a low delay requirement for the AV data based on the game title or the game genre extracted by the processing unit.
 9. The game system according to claim 5, wherein the processing unit extracts, from the game data, instruction information indicative of the presence or absence of a low delay requirement stored according to a game scene; the analysis unit determines whether a scene requires a low delay based on the instruction information preset for each scene; and the protocol setting unit receives a result of the determination provided by the analysis unit to set a communication protocol for each scene of the AV data.
 10. The game system according to claim 6, wherein the processing unit extracts, from the game data, instruction information indicative of the presence or absence of a low delay requirement stored according to a game scene; the analysis unit determines whether a scene requires a low delay based on the instruction information preset for each scene; and the protocol setting unit receives a result of the determination provided by the analysis unit to set a communication protocol for each scene of the AV data.
 11. A game data transmission method for transmitting AV data of a game to a receiving terminal over a network, comprising extracting preset instruction information from the game data; determining the presence or absence of a low delay requirement for the AV data based on the extracted instruction information: and receiving a result of the determination to set a communication protocol for the AV data.
 12. The game data transmission method according to claim 11, wherein the extracting step extracts, as instruction information, a game title or a game genre preset in the game data; and with reference to a table relating a game title to the presence or absence of a low delay requirement or a table relating a game genre to the presence or absence of a low delay requirement, the determining step determines the presence or absence of a low delay requirement for the AV data based on the game title or the game genre extracted.
 13. The game data transmission method according to claim 12, wherein the extracting step extracts, from the game data, instruction information indicative of the presence or absence of a low delay requirement stored according to a game scene; the determining step determines whether a scene requires a low delay based on the instruction information preset for each scene; and the protocol setting step receives a result of the determination to set a communication protocol for each scene of the AV data. 